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11/1 What Would A Bird Say?

If we could ask this Common Yellowthroat what she thinks of our efforts to improve the forest, I suspect she would not be impressed. She might say “what happened to the tangles?” In the past six years we’ve lopped and sawed our way through acres of invasive plants. But what have we done for wildlife, especially birds? We’ve mostly taken away, not replaced.

The tangle in the pic below has not been attacked with loppers and saws yet; it’s undoubtedly full of Bush honeysuckle but it’s also habitat. Food and shelter are available here and safe nesting sites

Within a tangle there are often well hidden nests..

such as this grapevine tendril creation cradling two Cardinal eggs.

This “improved” part of the forest may be lovely to the human eye, but from a bird’s point of view something is seriously lacking. What we appreciate in a forested landscape – a view through the trees – doesn’t offer much to the creatures who live here.

The problem is even more apparent in this early spring view; with all invasive plants removed, this forest has no “filling”. Imagine if someone took the walls off your house, that’s likely how it feels to the creatures who live here.

Back in the day, when we were new to the idea of removing invasives, it seemed that taking them out would solve all the forest’s problems. We could cut down whole swaths of “old growth” Bush Honeysuckle, and the devastation made us feel we’d accomplished something good. But now I’m not so sure…

Having nearly finished off this huge cluster of Multiflora Rose, Rosa multiflora, I was attacked by doubts – what about the shelter value of this thorny mass? Admittedly Multiflora is a highly invasive plant, particularly on open sites. And it’s so for a reason – birds and other animals relish the sweet abundant “hips” the plant produces. What did I have to give back for the food and shelter I was removing?

This gets to the heart of the problem – where are the native plants that could replace the non-native invasive ones? After all, the invasive plant takeover in our forest is relatively recent. Something else must have grown here at one time. Turns out, we have some other big problems that complicate native plant recovery…

Deer are literally big creatures, and as herbivores they need to eat all the time to sustain themselves. Going back and forth across the landscape like furry pruning shears, they selectively take out the tasty stuff and leave the rest. Not surprisingly, most non-native invasive plants are in the “rest” category.

The writer received a fellowship to study the impacts of large mammal herbivory on forests in northern Europe. Her observations on the state of Scottish forests could have been written for our preserve:

“All of a sudden I realised something is missing from most Scottish woods… Several hundred years of deer and sheep browsing has left our woods without their “filling” – there is the canopy and the ground, but everything in between these layers has been eaten out. Our woods are like the “sandwich without the filling” –“the burger with only the bun”!

As woodland managers and advisors we have for so long been so focussed on getting tree regeneration that we have seem to have failed to notice that woods are actually much more than just the trees. Even if the trees regenerate, without all the other climbing and trailing plants, shrubs, fruit bushes and tall herbs they will never be “woodland”; just a load of trees.”

But we can’t just blame the deer. Our little fragment actually looks more like a forest now than it has at any time in the past few hundred years. Considering the effects of agriculture, logging, wetland draining, creek channelization, cattle grazing, etc. – it’s surprising that any native forbs and shrubs are left. So no matter how many invasive plants are removed, what’s most likely to grow back is just more invasive plants. The technical name for this problem is a “depauperate seed bank”.

This raccoon scat displays some of the future contents of the seed bank, including seeds of Hackberry and Bush Honeysuckle

Thankfully one native shrub in particular has survived in some less disturbed pockets of woodland, and it can survive deer browsing as well.

If you’ve been reading this blog for awhile, you’ll know its name. Spicebush, Lindera benzoin is very common in forests of the Eastern US, particularly on moist bottomland. In fact, early settlers considered its presence an indicator of good soil. Nearly deer-proof, it’s one of those keystone species that makes up the “filling” of many an eastern forest. Lindera’s fatty red berries can be almost as prolific as those of Bush Honeysuckle, with much better nutritional value for birds. It’s making a comeback in our forest, but it can use some help.

In the next post, I’ll tell the story of our fledgling efforts to help this forest get its stuffing and tangles back. I recently read this section of our preserve management plan:

It’s a hard lesson to realize that all that work has not necessarily accomplished an improvement in habitat – at least not yet. Future posts will dwell on ways to “revive” more endemic plants, even in the presence of deer.

sbnightingale

It’s good to hear someone mention the importance of other vegetation found in our forests! When I go out and do Timber Stand Improvement (TSI) marking there is often little consideration of the woodlands as a whole. Our understory and midstory vegetation is just as important to the health of the forest ecosystem. Some private land owners are managing there woods for the purpose of a future harvest but that’s no reason to neglect the overall health of the woodlands.
Thank you!

Thanks for your support! With all the focus on tree planting, I think there’s not much awareness of how layered a forest should be. It’s certainly a challenge in our urban “deer preserve” to encourage the revival of native plants of any size.

Thanks Greg! Yes, wildlife certainly does like the berries and cover that many invasives provide. I am changing my attitude a bit about those tangles since they’re impossible to eradicate for good. Maybe a realistic happy medium is an urban forest with healthy regeneration of native plants, that helps keep invasive ones in check.